Graffiti of the fictional character Slender Man drawn on a street in Raleigh, N.C. / mdl70/Wikipedia

by Michael Winter, USA TODAY

by Michael Winter, USA TODAY

Two 12-year-old Wisconsin girls were charged as adults Monday for allegedly stabbing a friend 19 times after acting out bizarre instructions from an Internet site featuring horror stories, authorities said.

Morgan Geyser and Anissa Weier are being held for attempted first-degree intentional homicide over the Saturday morning attack in woods in the southeastern Wisconsin city of Waukesha.

The unidentified 12-year-old victim was fighting for her life in a hospital Monday, the Milwaukee Journal Sentinel reported.

According to the criminal complaint, one girl held the victim down and the other stabbed her in the torso, legs and arms, intending to kill her to become "proxies" of a character on the site Creepypasta Wiki, which posts short stories "designed to unnerve and shock the reader."

Despite her injuries, the victim crawled to a road, where a bicyclist found her. Police apprehended the two suspects Saturday afternoon and recovered a knife apparently used in the attack.

"Creepypasta" derives from the Internet slang "copypasta," a text block copied and pasted repeatedly on numerous websites. Its formulaic stories often include anecdotes, rituals or lost episodes of TV shows.

Rituals include a "list of instructions for the reader, claiming that if they go to a certain place at a certain time, and perform specific actions, something remarkable and/or horrifying will happen," the site says.

Weier told investigators that she introduced Geyser to the site in December, and that Geyser later decided they needed to kill someone to prove they were worthy of "Slenderman," the alleged leader of Creepypasta.

The pair decided to carry out the attack on May 30, Geyser's birthday, and then visit "Slender" at his mansion in the Nicolet National Forest to prove he existed.

"As the details became more apparent, it's extremely disturbing as a parent and as a chief of police, especially with the age of the suspects and being female," said Police Chief Russell Jack. "This is a very disturbing investigation."

He called it "a wake-up call for parents" to monitor their children's Internet use.

Members of Geyser's family sobbed several times during her court appearance.

"The family is very horrified at what has happened," attorney Donna Kuchler said.